Bump org.apache.kafka:kafka-clients from 3.7.1 to 3.9.1 in /kafka (#693)

Bumps org.apache.kafka:kafka-clients from 3.7.1 to 3.9.1.

---
updated-dependencies:
- dependency-name: org.apache.kafka:kafka-clients
  dependency-version: 3.9.1
  dependency-type: direct:production
...

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kafka/pom.xml

@@ -31,7 +31,7 @@
     <packaging>jar</packaging>
 
     <properties>
-        <kafka.version>3.7.1</kafka.version>
+        <kafka.version>3.9.1</kafka.version>
         <module-name>io.cloudevents.kafka</module-name>
     </properties>